上传图片问题报IllegalStateException

<jsp:useBean id="su" scope="page" class="com.jspsmart.upload.SmartUpload"/>
<%
 su.initialize(config,request,response);
 su.initialize(pageContext);
 su.setMaxFileSize(10000000);
 su.setTotalMaxFileSize(50000000);
 su.setAllowedFilesList("bmp,gif,jpg,jpeg");
 su.setDeniedFilesList("exe,bat,jsp,htm,html");
 su.upload(); int xx=Integer.parseInt((String)session.getAttribute("x"));
 String []img={null,null,null,null,null,null};
 for(int i=0;i<su.getFiles().getCount();i++)
 {
    File file=su.getFiles().getFile(i);
    if(file.isMissing()) 
    continue;
    Date date=new Date();
    String file_name=String.valueOf(date.getTime());
    double rand=Math.random()*10000;
    String ran=String.valueOf(rand);
    String part=ran.substring(0,4);
    file.saveAs("D:/news/WebRoot/shoppingimg/"+file_name+part+"."+su.getFiles().getFile(i).getFileExt());
    session.setAttribute("img"+i,file_name+part+"."+su.getFiles().getFile(i).getFileExt());
 }
response.sendRedirect("../Stockcontrol/adddata.jsp");
%>报错：
java.lang.IllegalStateException
org.apache.coyote.tomcat5.CoyoteResponseFacade.sendRedirect(CoyoteResponseFacade.java:353)
org.apache.jsp.Stockcontrol.uploadimg_jsp._jspService(uploadimg_jsp.java:214)
org.apache.jasper.runtime.HttpJspBase.service(HttpJspBase.java:94)
javax.servlet.http.HttpServlet.service(HttpServlet.java:802)
org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:324)
org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:292)
org.apache.jasper.servlet.JspServlet.service(JspServlet.java:236)
javax.servlet.http.HttpServlet.service(HttpServlet.java:802)